Applied Passive-solar Structural Design - Home Energy Pros2015-03-03T20:23:55Zhttp://homeenergypros.lbl.gov/forum/topics/applied-passive-solar-structural-design?commentId=6069565%3AComment%3A76878&feed=yes&xn_auth=noHi Tom, I looked over your pl…tag:homeenergypros.lbl.gov,2012-04-02:6069565:Comment:810652012-04-02T16:01:38.159ZBill Bradburyhttp://homeenergypros.lbl.gov/profile/BillBradbury
<p>Hi Tom, I looked over your plans a little closer this morning and there are a couple other comments that I would like to make.</p>
<p>PVC is not a good choice for water pipes, since it has a low heat transfer coefficient, is prone to fracture spirally if the water inside freezes and they are toxic. Black poly-pipe is fine for an open loop system (if you are going to use on open unpressurized tank or fountain), but if you are going closed loop, then you want PEX.</p>
<p>Solar gain on clear…</p>
<p>Hi Tom, I looked over your plans a little closer this morning and there are a couple other comments that I would like to make.</p>
<p>PVC is not a good choice for water pipes, since it has a low heat transfer coefficient, is prone to fracture spirally if the water inside freezes and they are toxic. Black poly-pipe is fine for an open loop system (if you are going to use on open unpressurized tank or fountain), but if you are going closed loop, then you want PEX.</p>
<p>Solar gain on clear days will make the cabin oh so warm and toasty, but what about the weeks where the wind blows 70 mph and the temps stay below zero? Then some of Dave's insulation and air sealing details become important.</p>
<p>I love clay! I live in a clay house and I use clay on almost every remodel I do. Clay is THE BEST thermal storage medium, with the added benefits of low cost, low maintenance and RH moderation. I guess what I'm trying to suggest is less water and a clay floor and/or walls.</p>
<p>For your exterior, I would recommend local pine or fir installed vertically over horizontal battens. I like 1x10 boards caulked together and 1x3 battens over the seams. Then stained with <a href="http://www.penofin.com/" target="_blank">Penofin</a> Brazilian Rosewood oil which blocks 99% UV.</p>
<p>Good luck, it's great to see somebody really thinking outside of the box.</p>
<p></p> Thank you Bill, using the air…tag:homeenergypros.lbl.gov,2012-03-31:6069565:Comment:811362012-03-31T15:36:23.291ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
<p>Thank you Bill, using the air-space between studs is more like Balloon Framing for sure. We'll see what the spiders do ... the floor insulation is removable for cleaning or if a pipe leaks.</p>
<p>Using pvc pipes for thermal-storage is the feature that matters most tho', collecting heat is pretty easy. For control, the roof vent shuts down at 40F, yet on a clear day in winter the solar wall gains ... we'll see how it goes.</p>
<p>I think for a home where the crawl-space was being revamped it…</p>
<p>Thank you Bill, using the air-space between studs is more like Balloon Framing for sure. We'll see what the spiders do ... the floor insulation is removable for cleaning or if a pipe leaks.</p>
<p>Using pvc pipes for thermal-storage is the feature that matters most tho', collecting heat is pretty easy. For control, the roof vent shuts down at 40F, yet on a clear day in winter the solar wall gains ... we'll see how it goes.</p>
<p>I think for a home where the crawl-space was being revamped it makes sense to install the pipes and use forced-air to move warm air to store heat below the floor.</p>
<p>A warm floor is so rare, it's amazing the difference in the room because cold air can't sit down low.</p>
<p>I also think the roof collection will tip the scale but we'll see. Latest thoughts are on how to finish the exterior to look forest-like.</p> Hi Tom, this is a great idea…tag:homeenergypros.lbl.gov,2012-03-31:6069565:Comment:809902012-03-31T14:08:49.884ZBill Bradburyhttp://homeenergypros.lbl.gov/profile/BillBradbury
<p>Hi Tom, this is a great idea that has been in use for at least 100 years, but is rarely used because it is poorly understood, so I love that you guys have dissected and explained the science behind it. The nea-sayers have not tried it.</p>
<p>Last winter I installed something similar on an off-grid clients home and they are over the moon. They only have wood heat, so they really appreciate not building fires in the shoulder seasons, but the performance in the heart of winter is only marginal…</p>
<p>Hi Tom, this is a great idea that has been in use for at least 100 years, but is rarely used because it is poorly understood, so I love that you guys have dissected and explained the science behind it. The nea-sayers have not tried it.</p>
<p>Last winter I installed something similar on an off-grid clients home and they are over the moon. They only have wood heat, so they really appreciate not building fires in the shoulder seasons, but the performance in the heart of winter is only marginal because of glazing losses.</p>
<p>The other great solar collector is your roof. A small fan with a differential temp controller blows warm air from the attic into the house. Also great for shoulder seasons, but not so good when it is -20F.</p>
<p>Check out <a href="http://www.heat-booster.com/index.html" target="_blank">http://www.heat-booster.com/index.html</a> for pre-fab versions of both.</p>
<p>Love the cabin pics, especially the worker housing(tents).</p> Posted all the drawings to Pi…tag:homeenergypros.lbl.gov,2012-03-30:6069565:Comment:811322012-03-30T15:09:29.814ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
<p>Posted all the drawings to Picasa, the figures are all over and end up being the lumber list, a pressure diagram, heat-transfer and building details to have the whole work as a circulation.</p>
<p>By adding another 1-1/2" insulated board 1/2" below the roof plywood when the sun is overhead it adds to the gain, using greenhouse plungers to open/close a custom vent for this.</p>
<p>The pipes between joists &amp; studs hold about 4-tons of water as thermal mass, thermo-panes with standard glass…</p>
<p>Posted all the drawings to Picasa, the figures are all over and end up being the lumber list, a pressure diagram, heat-transfer and building details to have the whole work as a circulation.</p>
<p>By adding another 1-1/2" insulated board 1/2" below the roof plywood when the sun is overhead it adds to the gain, using greenhouse plungers to open/close a custom vent for this.</p>
<p>The pipes between joists &amp; studs hold about 4-tons of water as thermal mass, thermo-panes with standard glass on the window wall with an added single layer to create the air-gap for heating the first 8-ft, manual insulation to close when no one is there for the top 4-ft sections.</p>
<p>It's a bunkhouse so there's seating and a loft above that, small pot-belly stove in the center &amp; drying space, boots &amp; coats &amp; gloves ...</p>
<p><a href="https://picasaweb.google.com/111702438340332674503/MilliwaysAPassiveSolarCabin">https://picasaweb.google.com/111702438340332674503/MilliwaysAPassiveSolarCabin</a>#</p>
Detail drawing of a constru…tag:homeenergypros.lbl.gov,2012-02-23:6069565:Comment:781102012-02-23T16:05:34.117ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
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<p>Detail drawing of a construction method to direct flow to under the roof when it's hot into the room circulation using a custom vent with a greenhouse plunger to open-close with temp changes. For a cabin on a forested ridge the roof offers a lot of heat when the sun is overhead for a couple hours with no shade, too big an opportunity to gain heat to ignore with a shaded site.…</p>
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<p>Detail drawing of a construction method to direct flow to under the roof when it's hot into the room circulation using a custom vent with a greenhouse plunger to open-close with temp changes. For a cabin on a forested ridge the roof offers a lot of heat when the sun is overhead for a couple hours with no shade, too big an opportunity to gain heat to ignore with a shaded site.</p>
<p><a href="http://api.ning.com:80/files/zcN4*xGdgtRd4LLihPN8tzjWw4gWa8doaLdF5K23IUMY5oqe0o9LPrrc5FZf30KWJpm*8COxQdSx*0nljVxeN1RPbyAknU1l/roofcirculation.jpg" target="_self"><img class="align-center" src="http://api.ning.com:80/files/zcN4*xGdgtRd4LLihPN8tzjWw4gWa8doaLdF5K23IUMY5oqe0o9LPrrc5FZf30KWJpm*8COxQdSx*0nljVxeN1RPbyAknU1l/roofcirculation.jpg?width=721" width="721"/></a></p> This page has been edited sin…tag:homeenergypros.lbl.gov,2012-02-11:6069565:Comment:768782012-02-11T17:13:20.797ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
<p>This page has been edited since making it, but close on figuring out circulation from thermal gain with volumes, used Bud's diagram to base pressure. The solar-gain wall produces about 64-cubic feet of flow per hour, expanding 2-1/8" over 8ft in the 1/2" space gaining 100F and at 8ft venting into the room of 1,232-cf with a peak at 12ft connected when conditions allow to the roof-space above the insulation of 55.2-cf, return inlet to the opposite wall at 10ft having 27.2-cf of thermal-mass,…</p>
<p>This page has been edited since making it, but close on figuring out circulation from thermal gain with volumes, used Bud's diagram to base pressure. The solar-gain wall produces about 64-cubic feet of flow per hour, expanding 2-1/8" over 8ft in the 1/2" space gaining 100F and at 8ft venting into the room of 1,232-cf with a peak at 12ft connected when conditions allow to the roof-space above the insulation of 55.2-cf, return inlet to the opposite wall at 10ft having 27.2-cf of thermal-mass, its air-volume 6.6-cf, this the vertical wall that spans the change in temp from ceiling to floor, then back under the floor of 78-cf air 104-cf thermal-mass to the inlet of the solar wall. Air is never below 40% humidity and above 60% most of the time.</p>
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<p><a href="http://api.ning.com:80/files/JFxztbhrCqaFgoIlAfQnfrlduziW6wwUtXdoazcW1o8Td3UkBDHskSB1OvzBfjhWiK2kD4nCUBGs-f56v4GZ*LiMvtTOMEan/thermalair_.jpg" target="_self"><img style="padding: 6px;" class="align-center" src="http://api.ning.com:80/files/JFxztbhrCqaFgoIlAfQnfrlduziW6wwUtXdoazcW1o8Td3UkBDHskSB1OvzBfjhWiK2kD4nCUBGs-f56v4GZ*LiMvtTOMEan/thermalair_.jpg" width="559"/></a></p> Left-coaster in the Seattle a…tag:homeenergypros.lbl.gov,2012-02-02:6069565:Comment:763702012-02-02T16:00:00.309ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
<p>Left-coaster in the Seattle area Johnny, will check out your sites, your comment made me think of a fixed camera mount or three, time-lapse style, to record this one ... for this group got this recent post on retro-fits being greener than new!! ... very interesting: <a href="http://www.bdcnetwork.com/blog/retrofits-almost-always-more-sustainable-new-green-construction">http://www.bdcnetwork.com/blog/retrofits-almost-always-more-sustainable-new-green-construction</a></p>
<p>As a design…</p>
<p>Left-coaster in the Seattle area Johnny, will check out your sites, your comment made me think of a fixed camera mount or three, time-lapse style, to record this one ... for this group got this recent post on retro-fits being greener than new!! ... very interesting: <a href="http://www.bdcnetwork.com/blog/retrofits-almost-always-more-sustainable-new-green-construction">http://www.bdcnetwork.com/blog/retrofits-almost-always-more-sustainable-new-green-construction</a></p>
<p>As a design problem I considered the typical Arctic flown-in cabin on piers during winter, no sun. Working on improving that led to knowing that the only rational place for thermal mass is under the floor, so, this is an attempt at actively moving the heat back down below the floor at mid-latitude all year, homes need a thermal bank for inertia to a change in temperature.</p> Tom, I've been wanting to add…tag:homeenergypros.lbl.gov,2012-02-02:6069565:Comment:761742012-02-02T15:24:11.990ZJohn Pitekhttp://homeenergypros.lbl.gov/profile/JohnPitek
<p>Tom, I've been wanting to add a passive solar section to my educational energy site, <a href="http://www.johnnyonenergy.com" target="_blank">Johnny on Energy</a>, and I'm looking for opportunities to film videos of homes or additions that are complete or under construction. I also have a personal interest as I intend to downsize and build a passive home when my two college studuents graduate. This PV solar home tour is a good example of a video on my site…</p>
<p>Tom, I've been wanting to add a passive solar section to my educational energy site, <a href="http://www.johnnyonenergy.com" target="_blank">Johnny on Energy</a>, and I'm looking for opportunities to film videos of homes or additions that are complete or under construction. I also have a personal interest as I intend to downsize and build a passive home when my two college studuents graduate. This PV solar home tour is a good example of a video on my site <a href="http://www.johnnyonenergy.com/solar-energy-facts-2/solar-residential-tour/" target="_blank">Solar Residential</a> in which a company called Alt Energy provides the tour. I'm located in Central, VA. So there is no confusion, we do not charge anyone to be on our site. We're happy to have them contribute and we always put in a good word for them and link back to their sites so that the reader can learn more.</p>
<p>If you're reading this and you're an energy auditor in my area I'd also like to add a few videos on the value of a home inspection and what the home owner can expect. There is a contact link on my site.</p>
<p>Thanks, Johnny P</p>
<p> </p> David, what does that typical…tag:homeenergypros.lbl.gov,2012-02-01:6069565:Comment:762692012-02-01T06:39:45.329ZTom Mallardhttp://homeenergypros.lbl.gov/profile/TomMallard
<p>David, what does that typically cost a square foot at today's pricing? I want your best ballpark low-to-high of getting it done by a contractor or DYI'er.</p>
<p>It's a much bigger list than I have for sure, but, I see nothing on solar-gain or thermal-mass in the list so even with this dandy upgrade and super-sealing it's a heat-loser!!</p>
<p>So you're bills did go down heavily but you're not off-the-grid to stay warm so I fail to see where what you descibe fits a ridge-top cabin with no…</p>
<p>David, what does that typically cost a square foot at today's pricing? I want your best ballpark low-to-high of getting it done by a contractor or DYI'er.</p>
<p>It's a much bigger list than I have for sure, but, I see nothing on solar-gain or thermal-mass in the list so even with this dandy upgrade and super-sealing it's a heat-loser!!</p>
<p>So you're bills did go down heavily but you're not off-the-grid to stay warm so I fail to see where what you descibe fits a ridge-top cabin with no utilities that'll have a wood stove?</p>
<p>To get more technical about how much insulation you need for any home an issue with me is that you not have studs with outside sheathing on them, this forces the heat-transfer into a much smaller area on the exterior facing walls, so every 16" you have a stud of heat-transfer trying to get through the outside insulation instead of transferring heat from the studs to sheathing on the outside which acts like a radiator so you radiate from the studs to 100% of the wall exterior, insulated or not.</p>
<p>What that means is my R19 is worth R30 on a side wall by thermal design, about a third more efficient by how the pieces are placed. Is there a coefficient you use for assorted wall gemetries or do you analyze those? It makes a huge difference in how much insulation you need by disallowing heat-flow paths.</p>
<p>But, the design still loses a ton through the windows and that's why thermal-mass is important to make a daily cycle and why I'm adding more water-filled pipes [now up to 1,200kg of water storage].</p>
<p>And, you keep wanting to cover the crawl space but your designs do not have thermal-mass storing heat in the floor radiating 24x7 to keep it warm.</p>
<p>That's a key issue with me now, by having it there the crawl-space soil becomes a thermal-mass that helps maintain the heat of the home over time by moving the equalibrium point far enough away to operate in this fashion. Just like a dug-in home but it's below the floor where you want it.</p>
<p>As I stated, what I suggest doing is dig up a couple feet of it and place insulation down with the dirt back on top of it to contain it specific as storage for the home above instead of continuing to heat soil over time.</p>
<p>This for homes is cheap thermal mass to consider gaining if you're installing heat distribution and thermal-mass below the floor, otherwise trying to seal it all off works fine and far better than doing nothing as many older homes show.</p> Tom,
I'm assuming all previou…tag:homeenergypros.lbl.gov,2012-01-31:6069565:Comment:763292012-01-31T16:47:25.341ZDavid Eakinhttp://homeenergypros.lbl.gov/profile/DavidEakin
<p>Tom,</p>
<p>I'm assuming all previous building descriptions apply to this 12x12 cabin (i.e., not new construction). I'd propose: sealing the crawlspace dirt floor, sealing rim joist area and insulating the crawlspace walls as previously described (keeps ground moisture in the ground; does not expose it to ambient air for mold/fungus growth; moves the conditioned space to include the crawl) - you can use the space for whatever afterward; remove all North/East/West windows and convert the…</p>
<p>Tom,</p>
<p>I'm assuming all previous building descriptions apply to this 12x12 cabin (i.e., not new construction). I'd propose: sealing the crawlspace dirt floor, sealing rim joist area and insulating the crawlspace walls as previously described (keeps ground moisture in the ground; does not expose it to ambient air for mold/fungus growth; moves the conditioned space to include the crawl) - you can use the space for whatever afterward; remove all North/East/West windows and convert the area to wall (too hard to regulate E/W solar gain; N exposure is a total loss); fill all interior cracks with silicone caulk or expanding foam (see referenced sources for air barrier checklists); R-19 sidewalls and R-30 ceiling will not even pass code for new construction so it is not better - increase side wall R value by applying 2 layers of R-12 polyisocyanurate foam sheeting (tape all joints with UL-181, stagger all joints), apply water drainage plane material, fasten 1x3 strapping with epoxy-coated screws for a siding base (see Mass. barn retrofit @ Building Science Corp.), seal off any soffit areas (plain construction/vents/etc) and apply foam panels to roof deck to achieve at least R-49 (more is better), apply water drainage material/strapping/roofing material (similar to walls; check references for examples); install un-faced fiberglass insulation in roof joist areas; apply (glue/screw) OSB to underside of roof joists, apply duct mastic or tape to joints to create new air seal (not the ceiling below) tied to the interior walls - use attic area to run wiring/venting/etc as this is now conditioned space; instead of plywood on the interior walls, use OSB (much better air seal) gluing it to all wall studs (constructs a "torque box" for stability), tape all seams (or use duct mastic) to create air barrier tied to roof air barrier; run surface wiring (or create additional hollow wall for wiring) so as not to penetrate the air barrier; anything that penetrates the air barrier (vent stack, etc.) must be sealed at the air barrier layer; integrate an air-to-air energy recovery ventilator unit (maybe solar-charged batteries if you are off the grid) with ducting to all rooms and pickup points at kitchen and bath (no kitchen/bath fans); DO NOT add any combustion appliance (stove, heater, range, water heater, etc.) that does not exhaust directly to the outside and receive combustion air from the outside; run any plumbing in interior walls; install insulated, tight-fitting window treatments on remaining glazing.</p>
<p>I'm guessing that you will not need any additional solar heat for space heating (but maybe for DHW) so you can eliminate all the other expenses for air circulation/storage/regulation/etc.; even the second layer of glazing.</p>
<p>This is not simplistic; it is modern building science (much of which has only really come to light the past 10 years or so). Look at the research material. Pay attention to details. Design for minimal air/thermal loss and proper (not random) air exchange.</p>